1. Field of the Invention
This invention relates in general to measuring devices and in particular to a novel type television camera measuring system.
2. Description of the Prior Art
Television systems have been used for measurement purposes however systems of the prior art normally had a relatively poor linearity and operational stability with regard to the geometry of the optical--electrical image conversion function and thus measurements made with such systems are often inaccurate. The reasons for these inaccuracies is that the horizontal deflection system which deflects the electron beam which scans the image of the object in a television camera tube such as a vidicon is subject to nonlinearity effects, drift effects and fluctuations which depend upon the operating temperature of the camera. Since the camera operates under widely differing temperature ranges such errors are common. One reason for the fluctuations which occur during temperature changes is that the camera components including the conductor leads have characteristics which vary as a function of temperature and thus as the temperature changes the amplitude of the horizontal deflection current will vary in the deflection system.
Since the amplitude of the horizontal deflection current determines the angle of the electron beam in the horizontal plane, variations in the horizontal deflection current will result in scanning rate changes and the scanning time within which a given object is scanned and it is this time which is used to represent a measure of the geometric width of an object. Thus variations in the amplitude of the horizontal deflection current cause inaccuracies in measurements made with such systems.